UVA1587

#include<iostream>
#include<cmath>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<iomanip>
#include<assert.h>
#include<vector>
#include<list>
#include<map>
#include<set>
#include<sstream>
#include<stack>
#include<queue>
#include<string>
#include<bitset>
#include<algorithm>
using namespace std;
#define me(s)  memset(s,0,sizeof(s))
#define _for(i,a,b) for(int i=(a);i<(b);++i)
#define _rep(i,a,b) for(int i=(a);i<=(b);++i)
#define mp make_pair
#define pb push_back
#define all(x) (x).begin(),(x).end()
#define F first
#define S second
#define Di(x) int x;scanf("%d",&x)
#define in(x) inp(x)
#define in2(x,y) inp(x),inp(y)
#define in3(x,y,z) inp(x),inp(y),inp(z)
#define ins(x) scanf("%s",x)
#define ind(x) scanf("%lf",&x)
#define IO ios_base::sync_with_stdio(0);cin.tie(0)
#define READ freopen("C:/Users/ASUS/Desktop/in.txt","r",stdin)
#define WRITE freopen("C:/Users/ASUS/Desktop/out.txt","w",stdout)
template<class T> void inp(T &x) {//读入优化
    char c = getchar(); x = 0;
    for (; (c < 48 || c>57); c = getchar());
    for (; c > 47 && c < 58; c = getchar()) { x = (x << 1) + (x << 3) + c - 48; }
}
typedef pair <int, int> pii;
typedef long long ll;
typedef unsigned long long ull;
const int inf = 0x3f3f3f3f;
const int mod = 1e9 + 7;
const double pi = acos(-1.0);
const double eps = 1e-15;
pii box[10];
int len[10],vis[10];

void Solve(){
    sort(box,box+6);
    bool ok=true;
    if(box[0]!=box[1]||box[2]!=box[3]||box[4]!=box[5]) ok=false;
    if(box[0].first!=box[2].first||box[4].first!=box[0].second||box[4].second!=box[2].second) ok=false;
    if(ok) printf("POSSIBLE\n");
    else printf("IMPOSSIBLE\n");
}
int Input(){
    if(scanf("%d%d",&box[0].first,&box[0].second)!=2) return 0;
    if(box[0].first>box[0].second) swap(box[0].first,box[0].second);
    _for(i,1,6) {
       scanf("%d%d",&box[i].first,&box[i].second);
       if(box[i].first>box[i].second) swap(box[i].first,box[i].second);
    }
    return 1;
}
int main(){
    //READ;
    //WRITE;
    while(Input())
    Solve();
}